Emotional self-regulation

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https://en.wikipedia.org/wiki/Emotional_self-regulation 

Emotional self-regulation or emotion regulation is the ability to respond to the ongoing demands of experience with the range of emotions in a manner that is socially tolerable and sufficiently flexible to permit spontaneous reactions as well as the ability to delay spontaneous reactions as needed. It can also be defined as extrinsic and intrinsic processes responsible for monitoring, evaluating, and modifying emotional reactions. Emotional self-regulation belongs to the broader set of emotion regulation processes, which includes both the regulation of one's own feelings and the regulation of other people's feelings.

Emotion regulation is a complex process that involves initiating, inhibiting, or modulating one's state or behavior in a given situation – for example, the subjective experience (feelings), cognitive responses (thoughts), emotion-related physiological responses (for example heart rate or hormonal activity), and emotion-related behavior (bodily actions or expressions). Functionally, emotion regulation can also refer to processes such as the tendency to focus one's attention to a task and the ability to suppress inappropriate behavior under instruction. Emotion regulation is a highly significant function in human life.

Every day, people are continually exposed to a wide variety of potentially arousing stimuli. Inappropriate, extreme or unchecked emotional reactions to such stimuli could impede functional fit within society; therefore, people must engage in some form of emotion regulation almost all of the time. Generally speaking, emotion dysregulation has been defined as difficulties in controlling the influence of emotional arousal on the organization and quality of thoughts, actions, and interactions. Individuals who are emotionally dysregulated exhibit patterns of responding in which there is a mismatch between their goals, responses, and/or modes of expression, and the demands of the social environment. For example, there is a significant association between emotion dysregulation and symptoms of depression, anxiety, eating pathology, and substance abuse. Higher levels of emotion regulation are likely to be related to both high levels of social competence and the expression of socially appropriate emotions.

Theory

Process model

The process model of emotion regulation is based upon the modal model of emotion. The modal model of emotion suggests that the emotion generation process occurs in a particular sequence over time. This sequence occurs as follows:

1. Situation: the sequence begins with a situation (real or imagined) that is emotionally relevant.
2. Attention: attention is directed towards the emotional situation.
3. Appraisal: the emotional situation is evaluated and interpreted.
4. Response: an emotional response is generated, giving rise to loosely coordinated changes in experiential, behavioral, and physiological response systems.

Because an emotional response (4.) can cause changes to a situation (1.), this model involves a feedback loop from (4.) Response to (1.) Situation. This feedback loop suggests that the emotion generation process can occur recursively, is ongoing, and dynamic.

The process model contends that each of these four points in the emotion generation process can be subjected to regulation. From this conceptualization, the process model posits five different families of emotion regulation that correspond to the regulation of a particular point in the emotion generation process. They occur in the following order:

1. Situation selection
2. Situation modification
3. Attentional deployment
4. Cognitive change
5. Response modulation

The process model also divides these emotion regulation strategies into two categories: antecedent-focused and response-focused. Antecedent-focused strategies (i.e., situation selection, situation modification, attentional deployment, and cognitive change) occur before an emotional response is fully generated. Response-focused strategies (i.e., response modulation) occur after an emotional response is fully generated.

Strategies

Situation selection

Situation selection involves choosing to avoid or approach an emotionally relevant situation. If a person selects to avoid or disengage from an emotionally relevant situation, he or she is decreasing the likelihood of experiencing an emotion. Alternatively, if a person selects to approach or engage with an emotionally relevant situation, he or she is increasing the likelihood of experiencing an emotion.

Typical examples of situation selection may be seen interpersonally, such as when a parent removes his or her child from an emotionally unpleasant situation. Use of situation selection may also be seen in psychopathology. For example, avoidance of social situations to regulate emotions is particularly pronounced for those with social anxiety disorder and avoidant personality disorder.

Effective situation selection is not always an easy task. For instance, humans display difficulties predicting their emotional responses to future events. Therefore, they may have trouble making accurate and appropriate decisions about which emotionally relevant situations to approach or to avoid.

Situation modification

Situation modification involves efforts to modify a situation so as to change its emotional impact. Situation modification refers specifically to altering one's external, physical environment. Altering one's "internal" environment to regulate emotion is called cognitive change.

Examples of situation modification may include injecting humor into a speech to elicit laughter or extending the physical distance between oneself and another person.

Attentional deployment

Attentional deployment involves directing one's attention towards or away from an emotional situation.

Distraction

Distraction, an example of attentional deployment, is an early selection strategy, which involves diverting one's attention away from an emotional stimulus and towards other content. Distraction has been shown to reduce the intensity of painful and emotional experiences, to decrease facial responding and neural activation in the amygdala associated with emotion, as well as to alleviate emotional distress. As opposed to reappraisal, individuals show a relative preference to engage in distraction when facing stimuli of high negative emotional intensity. This is because distraction easily filters out high-intensity emotional content, which would otherwise be relatively difficult to appraise and process.

Rumination

Rumination, an example of attentional deployment, is defined as the passive and repetitive focusing of one's attention on one's symptoms of distress and the causes and consequences of these symptoms. Rumination is generally considered a maladaptive emotion regulation strategy, as it tends to exacerbate emotional distress. It has also been implicated in a host of disorders including major depression.

Worry

Worry, an example of attentional deployment, involves directing attention to thoughts and images concerned with potentially negative events in the future. By focusing on these events, worrying serves to aid in the down-regulation of intense negative emotion and physiological activity. While worry may sometimes involve problem solving, incessant worry is generally considered maladaptive, being a common feature of anxiety disorders, particularly generalized anxiety disorder.

Thought suppression

Thought suppression, an example of attentional deployment, involves efforts to redirect one's attention from specific thoughts and mental images to other content so as to modify one's emotional state. Although thought suppression may provide temporary relief from undesirable thoughts, it may ironically end up spurring the production of even more unwanted thoughts. This strategy is generally considered maladaptive, being most associated with obsessive-compulsive disorder.

Cognitive change

Cognitive change involves changing how one appraises a situation so as to alter its emotional meaning.

Reappraisal

Reappraisal, an example of cognitive change, is a late selection strategy, which involves reinterpreting the meaning of an event so as to alter its emotional impact. For example, this might involve reinterpreting an event by broadening one's perspective to see "the bigger picture." Reappraisal has been shown to effectively reduce physiological, subjective, and neural emotional responding. As opposed to distraction, individuals show a relative preference to engage in reappraisal when facing stimuli of low negative emotional intensity because these stimuli are relatively easy to appraise and process.

Reappraisal is generally considered to be an adaptive emotion regulation strategy. Compared to suppression (including both thought suppression and expressive suppression), which is positively correlated with many psychological disorders, reappraisal can be associated with better interpersonal outcomes, and can be positively related to well-being. However, some researchers argue that context is important when evaluating the adaptiveness of a strategy, suggesting that in some contexts reappraisal may be maladaptive. Furthermore, some research has shown reappraisal does not influence affect or physiological responses to recurrent stress.

Distancing

Distancing, an example of cognitive change, involves taking on an independent, third-person perspective when evaluating an emotional event. Distancing has been shown to be an adaptive form of self-reflection, facilitating the emotional processing of negatively valenced stimuli, reducing emotional and cardiovascular reactivity to negative stimuli, and increasing problem-solving behavior.

Humor

Humor, an example of cognitive change, has been shown to be an effective emotion regulation strategy. Specifically, positive, good-natured humor has been shown to effectively up-regulate positive emotion and down-regulate negative emotion. On the other hand, negative, mean-spirited humor is less effective in this regard.

Response modulation

Response modulation involves attempts to directly influence experiential, behavioral, and physiological response systems.

Expressive suppression

Expressive suppression, an example of response modulation, involves inhibiting emotional expressions. It has been shown to effectively reduce facial expressivity, subjective feelings of positive emotion, heart rate, and sympathetic activation. However, the research findings are mixed regarding whether this strategy is effective for down-regulating negative emotion. Research has also shown that expressive suppression may have negative social consequences, correlating with reduced personal connections and greater difficulties forming relationships.

Expressive suppression is generally considered to be a maladaptive emotion regulation strategy. Compared to reappraisal, it is positively correlated with many psychological disorders, associated with worse interpersonal outcomes, is negatively related to well-being, and requires the mobilization of a relatively substantial amount of cognitive resources. However, some researchers argue that context is important when evaluating the adaptiveness of a strategy, suggesting that in some contexts suppression may be adaptive.

Drug use

Drug use, an example of response modulation, can be a way to alter emotion-associated physiological responses. For example, alcohol can produce sedative and anxiolytic effects and beta blockers can affect sympathetic activation.

Exercise

Exercise, an example of response modulation, can be used to down-regulate the physiological and experiential effects of negative emotions. Regular physical activity has also been shown to reduce emotional distress and improve emotional control.

Sleep

Sleep plays a role in emotion regulation, although stress and worry can also interfere with sleep. Studies have shown that sleep, specifically REM sleep, down-regulates reactivity of the amygdala, a brain structure known to be involved in the processing of emotions, in response to previous emotional experiences. On the flip side, sleep deprivation is associated with greater emotional reactivity or overreaction to negative and stressful stimuli. This is a result of both increased amygdala activity and a disconnect between the amygdala and the prefrontal cortex, which regulates the amygdala through inhibition, together resulting in an overactive emotional brain. Due to the subsequent lack of emotional control, sleep deprivation may be associated with depression, impulsivity, and mood swings. Additionally, there is some evidence that sleep deprivation may reduce emotional reactivity to positive stimuli and events and impair emotion recognition in others.

In psychotherapy

Emotion regulation strategies are taught, and emotion regulation problems are treated, in a variety of counseling and psychotherapy approaches, including Cognitive Behavioral Therapy (CBT), Dialectical Behavior Therapy (DBT), Emotion-Focused Therapy (EFT), and Mindfulness-Based Cognitive Therapy (MBCT).

For example, a relevant mnemonic formulated in DBT is "ABC PLEASE":

• Accumulate positive experiences.
• Build mastery by being active in activities that make one feel competent and effective to combat helplessness.
• Cope ahead, preparing an action plan, researching, and rehearsing (with a skilled helper if necessary).
• Physical illness treatment and prevention through checkups.
• Low vulnerability to diseases, managed with health care professionals.
• Eating healthy.
• Avoiding (non-prescribed) mood-altering drugs.
• Sleep healthy.
• Exercise regularly.

Developmental process

Infancy

Intrinsic emotion regulation efforts during infancy are believed to be guided primarily by innate physiological response systems. These systems usually manifest as an approach towards and an avoidance of pleasant or unpleasant stimuli. At three months, infants can engage in self-soothing behaviors like sucking and can reflexively respond to and signal feelings of distress. For instance, infants have been observed attempting to suppress anger or sadness by knitting their brow or compressing their lips. Between three and six months, basic motor functioning and attentional mechanisms begin to play a role in emotion regulation, allowing infants to more effectively approach or avoid emotionally relevant situations. Infants may also engage in self-distraction and help-seeking behaviors for regulatory purposes. At one year, infants are able to navigate their surroundings more actively and respond to emotional stimuli with greater flexibility due to improved motor skills. They also begin to appreciate their caregivers' abilities to provide them regulatory support. For instance, infants generally have difficulties regulating fear. As a result, they often find ways to express fear in ways that attract the comfort and attention of caregivers.

Extrinsic emotion regulation efforts by caregivers, including situation selection, modification, and distraction, are particularly important for infants. The emotion regulation strategies employed by caregivers to attenuate distress or to up-regulate positive affect in infants can impact the infants' emotional and behavioral development, teaching them particular strategies and methods of regulation. The type of attachment style between caregiver and infant can therefore play a meaningful role in the regulatory strategies infants may learn to use.

Recent evidence supports the idea that maternal singing has a positive effect on affect regulation in infants. Singing play-songs, such as "The Wheels on the Bus" or "She'll Be Comin' Round the Mountain" have a visible affect-regulatory consequence of prolonged positive affect and even alleviation of distress. In addition to proven facilitation of social bonding, when combined with movement and/or rhythmic touch, maternal singing for affect regulation has possible applications for infants in the NICU and for adult caregivers with serious personality or adjustment difficulties.

Toddler-hood

By the end of the first year, toddlers begin to adopt new strategies to decrease negative arousal. These strategies can include rocking themselves, chewing on objects, or moving away from things that upset them. At two years, toddlers become more capable of actively employing emotion regulation strategies. They can apply certain emotion regulation tactics to influence various emotional states. Additionally, maturation of brain functioning and language and motor skills permits toddlers to manage their emotional responses and levels of arousal more effectively.

Extrinsic emotion regulation remains important to emotional development in toddlerhood. Toddlers can learn ways from their caregivers to control their emotions and behaviors. For example, caregivers help teach self-regulation methods by distracting children from unpleasant events (like a vaccination shot) or helping them understand frightening events.

Childhood

Emotion regulation knowledge becomes more substantial during childhood. For example, children aged six to ten begin to understand display rules. They come to appreciate the contexts in which certain emotional expressions are socially most appropriate and therefore ought to be regulated. For example, children may understand that upon receiving a gift they should display a smile, irrespective of their actual feelings about the gift. During childhood, there is also a trend towards the use of more cognitive emotion regulation strategies, taking the place of more basic distraction, approach, and avoidance tactics.

Regarding the development of emotion dysregulation in children, one robust finding suggests that children who are frequently exposed to negative emotion at home will be more likely to display, and have difficulties regulating, high levels of negative emotion.

Adolescence

Adolescents show a marked increase in their capacities to regulate their emotions, and emotion regulation decision making becomes more complex, depending on multiple factors. In particular, the significance of interpersonal outcomes increases for adolescents. When regulating their emotions, adolescents are therefore likely to take into account their social context. For instance, adolescents show a tendency to display more emotion if they expect a sympathetic response from their peers.

Additionally, spontaneous use of cognitive emotion regulation strategies increases during adolescence, which is evidenced both by self-report data and neural markers.

Adulthood

Social losses increase and health tends to decrease as people age. As people get older their motivation to seek emotional meaning in life through social ties tends to increase. Autonomic responsiveness decreases with age, and emotion regulation skill tends to increase.

Emotional regulation in adulthood can also be examined in terms of positive and negative affectivity. Positive and negative affectivity refers to the types of emotions felt by an individual as well as the way those emotions are expressed. With adulthood comes an increased ability to maintain both high positive affectivity and low negative affectivity “more rapidly than adolescents.” This response to life’s challenges seems to become “automatized” as people progress throughout adulthood. Thus, as individuals age, their capability of self-regulating emotions and responding to their emotions in healthy ways improves.

Additionally, emotional regulation may vary between young adults and older adults. Younger adults have been found to be more successful than older adults in practicing “cognitive reappraisal” to decrease negative internal emotions. On the other hand, older adults have been found to be more successful in the following emotional regulation areas:

• Predicting the level of “emotional arousal” in possible situations
• Having a higher focus on positive information rather than negative
• Maintaining healthy levels of “hedonic well-being” (subjective well-being based on increased pleasure and decreased pain)

Overview of perspectives

Neuropsychological perspective

Affective

As people age, their affect – the way they react to emotions – changes, either positively or negatively. Studies show that positive affect increases as a person grows from adolescence to their mid 70s. Negative affect, on the other hand, decreases until the mid 70s. Studies also show that emotions differ in adulthood, particularly affect (positive or negative). Although some studies found that individuals experience less affect as they grow older, other studies have concluded that adults in their middle age experience more positive affect and less negative affect than younger adults. Positive affect was also higher for men than women while the negative affect was higher for women than it was for men and also for single people. A reason that older people – middle adulthood – might have less negative affect is because they have overcome, "the trials and vicissitudes of youth, they may increasingly experience a more pleasant balance of affect, at least up until their mid-70s". Positive affect might rise during middle age but towards the later years of life – the 70s – it begins to decline while negative affect also does the same. This might be due to failing health, reaching the end of their lives and the death of friends and relatives.

In addition to baseline levels of positive and negative affect, studies have found individual differences in the time-course of emotional responses to stimuli. The temporal dynamics of emotion regulation, also known as affective chronometry, include two key variables in the emotional response process: rise time to peak emotional response, and recovery time to baseline levels of emotion. Studies of affective chronometry typically separate positive and negative affect into distinct categories, as previous research has shown (despite some correlation) the ability of humans to experience changes in these categories independently of one another. Affective chronometry research has been conducted on clinical populations with anxiety, mood, and personality disorders, but is also utilized as a measurement to test the effectiveness of different therapeutic techniques (including mindfulness training) on emotional dysregulation.

Neurological

The development of functional magnetic resonance imaging has allowed for the study of emotion regulation on a biological level. Specifically, research over the last decade strongly suggests that there is a neural basis. Sufficient evidence has correlated emotion regulation to particular patterns of prefrontal activation. These regions include the orbital prefrontal cortex, the ventromedial prefrontal cortex, and the dorsolateral prefrontal cortex. Two additional brain structures that have been found to contribute are the amygdala and the anterior cingulate cortex. Each of these structures are involved in various facets of emotion regulation and irregularities in one or more regions and/or interconnections among them are affiliated with failures of emotion regulation. An implication to these findings is that individual differences in prefrontal activation predict the ability to perform various tasks in aspects of emotion regulation.

Sociological

People intuitively mimic facial expressions; it is a fundamental part of healthy functioning. Similarities across cultures in regards to nonverbal communication has prompted the debate that it is in fact a universal language. It can be argued that emotion regulation plays a key role in the ability to generate the correct responses in social situations. Humans have control over facial expressions both consciously and unconsciously: an intrinsic emotion program is generated as the result of a transaction with the world, which immediately results in an emotional response and usually a facial reaction. It is a well documented phenomenon that emotions have an effect on facial expression, but recent research has provided evidence that the opposite may also be true.

This notion would give rise to the belief that a person may not only control his emotion but in fact influence them as well. Emotion regulation focuses on providing the appropriate emotion in the appropriate circumstances. Some theories allude to the thought that each emotion serves a specific purpose in coordinating organismic needs with environmental demands (Cole, 1994). This skill, although apparent throughout all nationalities, has been shown to vary in successful application at different age groups. In experiments done comparing younger and older adults to the same unpleasant stimuli, older adults were able to regulate their emotional reactions in a way that seemed to avoid negative confrontation. These findings support the theory that with time people develop a better ability to regulate their emotions. This ability found in adults seems to better allow individuals to react in what would be considered a more appropriate manner in some social situations, permitting them to avoid adverse situations that could be seen as detrimental.

Expressive regulation (in solitary conditions)

In solitary conditions, emotion regulation can include a minimization-miniaturization effect, in which common outward expressive patterns are replaced with toned down versions of expression. Unlike other situations, in which physical expression (and its regulation) serve a social purpose (i.e. conforming to display rules or revealing emotion to outsiders), solitary conditions require no reason for emotions to be outwardly expressed (although intense levels of emotion can bring out noticeable expression anyway). The idea behind this is that as people get older, they learn that the purpose of outward expression (to appeal to other people), is not necessary in situations in which there is no one to appeal to. As a result, the level of emotional expression can be lower in these solitary situations.

Stress

The way an individual reacts to stress can directly overlap with their ability to regulate emotion. Although the two concepts differ in a multitude of ways, "both coping [with stress] and emotion regulation involve affect modulation and appraisal processes" that are necessary for healthy relationships and self-identity.

According to Yu. V. Shcherbatykh, emotional stress in situations like school examinations can be reduced by engaging in self-regulating activities prior to the task being performed. To study the influence of self-regulation on mental and physiological processes under exam stress, Shcherbatykh conducted a test with an experimental group of 28 students (of both sexes) and a control group of 102 students (also of both sexes).

In the moments before the examination, situational stress levels were raised in both groups from what they were in quiet states. In the experimental group, participants engaged in three self-regulating techniques (concentration on respiration, general body relaxation, and the creation of a mental image of successfully passing the examination). During the examination, the anxiety levels of the experimental group were lower than that of the control group. Also, the percent of unsatisfactory marks in the experimental group was 1.7 times less than in the control group. From this data, Shcherbatykh concluded that the application of self-regulating actions before examinations helps to significantly reduce levels of emotional strain, which can help lead to better performance results.

Decision making

Identification of our emotional self-regulating process can facilitate in the decision making process. Current literature on emotion regulation identifies that humans characteristically make efforts in controlling emotion experiences. There is then a possibility that our present state emotions can be altered by emotion regulation strategies resulting in the possibility that different regulation strategies could have different decision implications.

Effects of low self-regulation

With a failure in emotion regulation, there is a rise in psychosocial and emotional dysfunctions caused by traumatic experiences due to an inability to regulate emotions. These traumatic experiences typically happen in grade school and are sometimes associated with bullying. Children who can't properly self-regulate express their volatile emotions in a variety of ways, including screaming if they don't have their way, lashing out with their fists, throwing objects (such as chairs), or bullying other children. Such behaviors often elicit negative reactions from the social environment, which, in turn, can exacerbate or maintain the original regulation problems over time, a process termed cumulative continuity. These children are more likely to have conflict-based relationships with their teachers and other children. This can lead to more severe problems such as an impaired ability to adjust to school and predicts school dropout many years later. Children who fail to properly self-regulate grow as teenagers with more emerging problems. Their peers begin to notice this "immaturity", and these children are often excluded from social groups and teased and harassed by their peers. This "immaturity" certainly causes some teenagers to become social outcasts in their respective social groups, causing them to lash out in angry and potentially violent ways. Being teased or being an outcast in childhood is especially damaging because it could lead to psychological symptoms such as depression and anxiety (in which dysregulated emotions play a central role), which, in turn, could lead to more peer victimization. This is why it is recommended to foster emotional self-regulation in children as early as possible.

Hypothalamic–pituitary–adrenal axis

From Wikipedia, the free encyclopedia

 

 

Schematic of the HPA axis (CRH, corticotropin-releasing hormone; ACTH, adrenocorticotropic hormone)

Hypothalamus, pituitary gland and adrenal cortex

The hypothalamic–pituitary–adrenal axis (HPA axis or HTPA axis) is a complex set of direct influences and feedback interactions among three components: the hypothalamus, the pituitary gland (a pea-shaped structure located below the thalamus), and the adrenal (also called "suprarenal") glands (small, conical organs on top of the kidneys).

These organs and their interactions constitute the HPA axis, a major neuroendocrine system that controls reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality, and energy storage and expenditure. It is the common mechanism for interactions among glands, hormones, and parts of the midbrain that mediate the general adaptation syndrome (GAS). While steroid hormones are produced mainly in vertebrates, the physiological role of the HPA axis and corticosteroids in stress response is so fundamental that analogous systems can be found in invertebrates and monocellular organisms as well.

The HPA axis, hypothalamic–pituitary–gonadal axis (HPG), hypothalamic–pituitary–thyroid axis (HPT), and the hypothalamic–neurohypophyseal system are the four major neuroendocrine systems through which the hypothalamus and pituitary direct neuroendocrine function.

Anatomy

The key elements of the HPA axis are:

• The paraventricular nucleus of the hypothalamus, which contains neuroendocrine neurons which synthesize and secrete vasopressin and corticotropin-releasing hormone (CRH). These two peptides regulate:
  • The anterior lobe of the pituitary gland. In particular, CRH and vasopressin stimulate the secretion of adrenocorticotropic hormone (ACTH), once known as corticotropin. ACTH in turn acts on:
  • the adrenal cortex, which produces glucocorticoid hormones (mainly cortisol in humans) in response to stimulation by ACTH. Glucocorticoids in turn act back on the hypothalamus and pituitary (to suppress CRH and ACTH production) in a negative feedback cycle.

CRH and vasopressin are released from neurosecretory nerve terminals at the median eminence. CRH is transported to the anterior pituitary through the portal blood vessel system of the hypophyseal stalk and vasopressin is transported by axonal transport to the posterior pituitary gland. There, CRH and vasopressin act synergistically to stimulate the secretion of stored ACTH from corticotrope cells. ACTH is transported by the blood to the adrenal cortex of the adrenal gland, where it rapidly stimulates biosynthesis of corticosteroids such as cortisol from cholesterol. Cortisol is a major stress hormone and has effects on many tissues in the body, including the brain. In the brain, cortisol acts on two types of receptor – mineralocorticoid receptors and glucocorticoid receptors, and these are expressed by many different types of neurons. One important target of glucocorticoids is the hypothalamus, which is a major controlling centre of the HPA axis.

Vasopressin can be thought of as "water conservation hormone" and is also known as "antidiuretic hormone." It is released when the body is dehydrated and has potent water-conserving effects on the kidney. It is also a potent vasoconstrictor.

Important to the function of the HPA axis are some of the feedback loops:

• Cortisol produced in the adrenal cortex will negatively feedback to inhibit both the hypothalamus and the pituitary gland. This reduces the secretion of CRH and vasopressin, and also directly reduces the cleavage of proopiomelanocortin (POMC) into ACTH and β-endorphins.
• Epinephrine and norepinephrine (E/NE) are produced by the adrenal medulla through sympathetic stimulation and the local effects of cortisol (upregulation enzymes to make E/NE). E/NE will positively feedback to the pituitary and increase the breakdown of POMCs into ACTH and β-endorphins.

Function

Release of corticotropin-releasing hormone (CRH) from the hypothalamus is influenced by stress, physical activity, illness, by blood levels of cortisol and by the sleep/wake cycle (circadian rhythm). In healthy individuals, cortisol rises rapidly after wakening, reaching a peak within 30–45 minutes. It then gradually falls over the day, rising again in late afternoon. Cortisol levels then fall in late evening, reaching a trough during the middle of the night. This corresponds to the rest-activity cycle of the organism. An abnormally flattened circadian cortisol cycle has been linked with chronic fatigue syndrome, insomnia and burnout.

The HPA axis has a central role in regulating many homeostatic systems in the body, including the metabolic system, cardiovascular system, immune system, reproductive system and central nervous system. The HPA axis integrates physical and psychosocial influences in order to allow an organism to adapt effectively to its environment, use resources, and optimize survival.

Anatomical connections between brain areas such as the amygdala, hippocampus, prefrontal cortex and hypothalamus facilitate activation of the HPA axis. Sensory information arriving at the lateral aspect of the amygdala is processed and conveyed to the amygdala's central nucleus, which then projects out to several parts of the brain involved in responses to fear. At the hypothalamus, fear-signaling impulses activate both the sympathetic nervous system and the modulating systems of the HPA axis.

Increased production of cortisol during stress results in an increased availability of glucose in order to facilitate fighting or fleeing. As well as directly increasing glucose availability, cortisol also suppresses the highly demanding metabolic processes of the immune system, resulting in further availability of glucose.

Glucocorticoids have many important functions, including modulation of stress reactions, but in excess they can be damaging. Atrophy of the hippocampus in humans and animals exposed to severe stress is believed to be caused by prolonged exposure to high concentrations of glucocorticoids. Deficiencies of the hippocampus may reduce the memory resources available to help a body formulate appropriate reactions to stress.

Immune system

There is bi-directional communication and feedback between the HPA axis and the immune system. A number of cytokines, such as IL-1, IL-6, IL-10 and TNF-alpha can activate the HPA axis, although IL-1 is the most potent. The HPA axis in turn modulates the immune response, with high levels of cortisol resulting in a suppression of immune and inflammatory reactions. This helps to protect the organism from a lethal overactivation of the immune system, and minimizes tissue damage from inflammation.

The CNS is in many ways "immune privileged", but it plays an important role in the immune system and is affected by it in turn. The CNS regulates the immune system through neuroendocrine pathways, such as the HPA axis. The HPA axis is responsible for modulating inflammatory responses that occur throughout the body.

During an immune response, proinflammatory cytokines (e.g. IL-1) are released into the peripheral circulation system and can pass through the blood brain barrier where they can interact with the brain and activate the HPA axis. Interactions between the proinflammatory cytokines and the brain can alter the metabolic activity of neurotransmitters and cause symptoms such as fatigue, depression, and mood changes. Deficiencies in the HPA axis may play a role in allergies and inflammatory/ autoimmune diseases, such as rheumatoid arthritis and multiple sclerosis.

When the HPA axis is activated by stressors, such as an immune response, high levels of glucocorticoids are released into the body and suppress immune response by inhibiting the expression of proinflammatory cytokines (e.g. IL-1, TNF alpha, and IFN gamma) and increasing the levels of anti-inflammatory cytokines (e.g. IL-4, IL-10, and IL-13) in immune cells, such as monocytes and neutrophils 

The relationship between chronic stress and its concomitant activation of the HPA axis, and dysfunction of the immune system is unclear; studies have found both immunosuppression and hyperactivation of the immune response.

Stress

Schematic overview of the hypothalamic-pituitary-adrenal (HPA) axis. Stress activates the HPA-axis and thereby enhances the secretion of glucocorticoids from the adrenals.

Stress and disease

The HPA axis is involved in the neurobiology of mood disorders and functional illnesses, including anxiety disorder, bipolar disorder, insomnia, posttraumatic stress disorder, borderline personality disorder, ADHD, major depressive disorder, burnout, chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, and alcoholism. Antidepressants, which are routinely prescribed for many of these illnesses, serve to regulate HPA axis function.

Sex differences are prevalent in humans with respect to psychiatric stress-related disorders such as anxiety and depression, where women experience these disorders more often than men. Particularly in rodents, it has been shown that females may lack the ability to tolerate as well as process stress (particularly for chronic stress) due to possible down regulation of GR expression as well as a deficiency of FKBP51 binding protein in the cytosol. By constantly activating the HPA axis, this could lead to higher instances of stress and disorders that would only get worse with chronic stress. Specifically in rodents, females show greater activation of the HPA axis following stress than males. These differences also likely arise due to the opposing actions that certain sex steroids have, such as testosterone and oestrogen. Oestrogen functions to enhance stress-activated ACTH and CORT secretion while testosterone functions to decrease HPA axis activation and works to inhibit both ACTH and CORT responses to stress. However, more studies are required to better understand the underlying basis of these sex differences.

Experimental studies have investigated many different types of stress, and their effects on the HPA axis in many different circumstances. Stressors can be of many different types—in experimental studies in rats, a distinction is often made between "social stress" and "physical stress", but both types activate the HPA axis, though via different pathways. Several monoamine neurotransmitters are important in regulating the HPA axis, especially dopamine, serotonin and norepinephrine (noradrenaline). There is evidence that an increase in oxytocin, resulting for instance from positive social interactions, acts to suppress the HPA axis and thereby counteracts stress, promoting positive health effects such as wound healing.

The HPA axis is a feature of mammals and other vertebrates. For example, biologists studying stress in fish showed that social subordination leads to chronic stress, related to reduced aggressive interactions, to lack of control, and to the constant threat imposed by dominant fish. Serotonin (5HT) appeared to be the active neurotransmitter involved in mediating stress responses, and increases in serotonin are related to increased plasma α-MSH levels, which causes skin darkening (a social signal in salmonoid fish), activation of the HPA axis, and inhibition of aggression. Inclusion of the amino acid L-tryptophan, a precursor of 5HT, in the feed of rainbow trout made the trout less aggressive and less responsive to stress. However, the study mentions that plasma cortisol was not affected by dietary L-tryptophan. The drug LY354740 (also known as Eglumegad, an agonist of the metabotropic glutamate receptors 2 and 3) has been shown to interfere in the HPA axis, with chronic oral administration of this drug leading to markedly reduced baseline cortisol levels in bonnet macaques (Macaca radiata); acute infusion of LY354740 resulted in a marked diminution of yohimbine-induced stress response in those animals.

Studies on people show that the HPA axis is activated in different ways during chronic stress depending on the type of stressor, the person's response to the stressor and other factors. Stressors that are uncontrollable, threaten physical integrity, or involve trauma tend to have a high, flat diurnal profile of cortisol release (with lower-than-normal levels of cortisol in the morning and higher-than-normal levels in the evening) resulting in a high overall level of daily cortisol release. On the other hand, controllable stressors tend to produce higher-than-normal morning cortisol. Stress hormone release tends to decline gradually after a stressor occurs. In post-traumatic stress disorder there appears to be lower-than-normal cortisol release, and it is thought that a blunted hormonal response to stress may predispose a person to develop PTSD.

It is also known that HPA axis hormones are related to certain skin diseases and skin homeostasis. There is evidence shown that the HPA axis hormones can be linked to certain stress related skin diseases and skin tumors. This happens when HPA axis hormones become hyperactive in the brain.

Stress and development

Prenatal stress

There is evidence that prenatal stress can influence HPA regulation. In animal experiments, exposure to prenatal stress has been shown to cause a hyper-reactive HPA stress response. Rats that have been prenatally stressed have elevated basal levels and abnormal circadian rhythm of corticosterone as adults. Additionally, they require a longer time for their stress hormone levels to return to baseline following exposure to both acute and prolonged stressors. Prenatally stressed animals also show abnormally high blood glucose levels and have fewer glucocorticoid receptors in the hippocampus. In humans, prolonged maternal stress during gestation is associated with mild impairment of intellectual activity and language development in their children, and with behaviour disorders such as attention deficits, schizophrenia, anxiety and depression; self-reported maternal stress is associated with a higher irritability, emotional and attentional problems.

There is growing evidence that prenatal stress can affect HPA regulation in humans. Children who were stressed prenatally may show altered cortisol rhythms. For example, several studies have found an association between maternal depression during pregnancy and childhood cortisol levels. Prenatal stress has also been implicated in a tendency toward depression and short attention span in childhood. There is no clear indication that HPA dysregulation caused by prenatal stress can alter adult behavior.

Early life stress

The role of early life stress in programming the HPA Axis has been well-studied in animal models. Exposure to mild or moderate stressors early in life has been shown to enhance HPA regulation and promote a lifelong resilience to stress. In contrast, early-life exposure to extreme or prolonged stress can induce a hyper-reactive HPA Axis and may contribute to lifelong vulnerability to stress. In one widely replicated experiment, rats subjected to the moderate stress of frequent human handling during the first two weeks of life had reduced hormonal and behavioral HPA-mediated stress responses as adults, whereas rats subjected to the extreme stress of prolonged periods of maternal separation showed heightened physiological and behavioral stress responses as adults.

Several mechanisms have been proposed to explain these findings in rat models of early-life stress exposure. There may be a critical period during development during which the level of stress hormones in the bloodstream contribute to the permanent calibration of the HPA Axis. One experiment has shown that, even in the absence of any environmental stressors, early-life exposure to moderate levels of corticosterone was associated with stress resilience in adult rats, whereas exposure to high doses was associated with stress vulnerability.

Another possibility is that the effects of early-life stress on HPA functioning are mediated by maternal care. Frequent human handling of the rat pups may cause their mother to exhibit more nurturant behavior, such as licking and grooming. Nurturant maternal care, in turn, may enhance HPA functioning in at least two ways. First, maternal care is crucial in maintaining the normal stress hypo responsive period (SHRP), which in rodents, is the first two weeks of life during which the HPA axis is generally non-reactive to stress. Maintenance of the SHRP period may be critical for HPA development, and the extreme stress of maternal separation, which disrupts the SHRP, may lead to permanent HPA dysregulation. Another way that maternal care might influence HPA regulation is by causing epigenetic changes in the offspring. For example, increased maternal licking and grooming has been shown to alter expression of the glutocorticoid receptor gene implicated in adaptive stress response. At least one human study has identified maternal neural activity patterns in response to video stimuli of mother-infant separation as being associated with decreased glucocorticoid receptor gene methylation in the context of post-traumatic stress disorder stemming from early life stress. Yet clearly, more research is needed to determine if the results seen in cross-generational animal models can be extended to humans.

Though animal models allow for more control of experimental manipulation, the effects of early life stress on HPA axis function in humans has also been studied. One population that is often studied in this type of research is adult victims of childhood abuse. Adult victims of childhood abuse have exhibited increased ACTH concentrations in response to a psychosocial stress task compared to healthy controls and subjects with depression but not childhood abuse. In one study, adult victims of childhood abuse that are not depressed show increased ACTH response to both exogenous CRF and normal cortisol release. Adult victims of childhood abuse that are depressed show a blunted ACTH response to exogenous CRH. A blunted ACTH response is common in depression, so the authors of this work posit that this pattern is likely to be due to the participant's depression and not their exposure to early life stress.

Heim and colleagues have proposed that early life stress, such as childhood abuse, can induce a sensitization of the HPA axis, resulting in particular heightened neuronal activity in response to stress-induced CRF release. With repeated exposure to stress, the sensitized HPA axis may continue to hypersecrete CRF from the hypothalamus. Over time, CRF receptors in the anterior pituitary will become down-regulated, producing depression and anxiety symptoms. This research in human subjects is consistent with the animal literature discussed above.

The HPA Axis was present in the earliest vertebrate species, and has remained highly conserved by strong positive selection due to its critical adaptive roles. The programming of the HPA axis is strongly influenced by the perinatal and early juvenile environment, or “early-life environment.” Maternal stress and differential degrees of caregiving may constitute early life adversity, which has been shown to profoundly influence, if not permanently alter, the offspring's stress and emotional regulating systems. Widely studied in animal models (e.g. licking and grooming/LG in rat pups), the consistency of maternal care has been shown to have a powerful influence on the offspring's neurobiology, physiology, and behavior. Whereas maternal care improves cardiac response, sleep/wake rhythm, and growth hormone secretion in the neonate, it also suppresses HPA axis activity. In this manner, maternal care negatively regulates stress response in the neonate, thereby shaping his/her susceptibility to stress in later life. These programming effects are not deterministic, as the environment in which the individual develops can either match or mismatch with the former's “programmed” and genetically predisposed HPA axis reactivity. Although the primary mediators of the HPA axis are known, the exact mechanism by which its programming can be modulated during early life remains to be elucidated. Furthermore, evolutionary biologists contest the exact adaptive value of such programming, i.e. whether heightened HPA axis reactivity may confer greater evolutionary fitness.

Various hypotheses have been proposed, in attempts to explain why early life adversity can produce outcomes ranging from extreme vulnerability to resilience, in the face of later stress. Glucocorticoids produced by the HPA axis have been proposed to confer either a protective or harmful role, depending on an individual's genetic predispositions, programming effects of early-life environment, and match or mismatch with one's postnatal environment. The predictive adaptation hypothesis (1), the three-hit concept of vulnerability and resilience (2) and the maternal mediation hypothesis (3) attempt to elucidate how early life adversity can differentially predict vulnerability or resilience in the face of significant stress in later life. These hypotheses are not mutually exclusive but rather are highly interrelated and unique to the individual.

(1) The predictive adaptation hypothesis: this hypothesis is in direct contrast with the diathesis stress model, which posits that the accumulation of stressors across a lifespan can enhance the development of psychopathology once a threshold is crossed. Predictive adaptation asserts that early life experience induces epigenetic change; these changes predict or “set the stage” for adaptive responses that will be required in his/her environment. Thus, if a developing child (i.e., fetus to neonate) is exposed to ongoing maternal stress and low levels of maternal care (i.e., early life adversity), this will program his/her HPA axis to be more reactive to stress. This programming will have predicted, and potentially be adaptive in a highly stressful, precarious environment during childhood and later life. The predictability of these epigenetic changes is not definitive, however – depending primarily on the degree to which the individual's genetic and epigenetically modulated phenotype “matches” or “mismatches” with his/her environment (See: Hypothesis (2)).

(2) Three-Hit Concept of vulnerability and resilience: this hypothesis states that within a specific life context, vulnerability may be enhanced with chronic failure to cope with ongoing adversity. It fundamentally seeks to explicate why, under seemingly indistinguishable circumstances, one individual may cope resiliently with stress, whereas another may not only cope poorly, but consequently develop a stress-related mental illness. The three “hits” – chronological and synergistic – are as follows: genetic predisposition (which predispose higher/lower HPA axis reactivity), early-life environment (perinatal – i.e. maternal stress, and postnatal – i.e. maternal care), and later-life environment (which determines match/mismatch, as well as a window for neuroplastic changes in early programming). (Figure 1) The concept of match/mismatch is central to this evolutionary hypothesis. In this context, it elucidates why early life programming in the perinatal and postnatal period may have been evolutionarily selected for. Specifically, by instating specific patterns of HPA axis activation, the individual may be more well equipped to cope with adversity in a high-stress environment. Conversely, if an individual is exposed to significant early life adversity, heightened HPA axis reactivity may “mismatch” him/her in an environment characterized by low stress. The latter scenario may represent maladaptation due to early programming, genetic predisposition, and mismatch. This mismatch may then predict negative developmental outcomes such as psychopathologies in later life.

Ultimately, the conservation of the HPA axis has underscored its critical adaptive roles in vertebrates, so, too, various invertebrate species over time. The HPA Axis plays a clear role in the production of corticosteroids, which govern many facets of brain development and responses to ongoing environmental stress. With these findings, animal model research has served to identify what these roles are – with regards to animal development and evolutionary adaptation. In more precarious, primitive times, a heightened HPA axis may have served to protect organisms from predators and extreme environmental conditions, such as weather and natural disasters, by encouraging migration (i.e. fleeing), the mobilization of energy, learning (in the face of novel, dangerous stimuli) as well as increased appetite for biochemical energy storage. In contemporary society, the endurance of the HPA axis and early life programming will have important implications for counseling expecting and new mothers, as well as individuals who may have experienced significant early life adversity.

Fight-or-flight response

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Fight-or-flight_response 

Dog and cat showing acute stress responses

The fight-or-flight response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first described by Walter Bradford Cannon. His theory states that animals react to threats with a general discharge of the sympathetic nervous system, preparing the animal for fighting or fleeing. More specifically, the adrenal medulla produces a hormonal cascade that results in the secretion of catecholamines, especially norepinephrine and epinephrine. The hormones estrogen, testosterone, and cortisol, as well as the neurotransmitters dopamine and serotonin, also affect how organisms react to stress. The hormone osteocalcin might also play a part.

This response is recognised as the first stage of the general adaptation syndrome that regulates stress responses among vertebrates and other organisms.

Physiology

Autonomic nervous system

The autonomic nervous system is a control system that acts largely unconsciously and regulates heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response and its role is mediated by two different components: the sympathetic nervous system and the parasympathetic nervous system.

Sympathetic nervous system

The sympathetic nervous system originates in the spinal cord and its main function is to activate the physiological changes that occur during the fight-or-flight response. This component of the autonomic nervous system utilises and activates the release of norepinephrine in the reaction.

Parasympathetic nervous system

The parasympathetic nervous system originates in the sacral spinal cord and medulla, physically surrounding the sympathetic origin, and works in concert with the sympathetic nervous system. Its main function is to activate the "rest and digest" response and return the body to homeostasis after the fight or flight response. This system utilises and activates the release of the neurotransmitter acetylcholine.

Reaction

An infographic displaying the fight-or-flight response

The reaction begins in the amygdala, which triggers a neural response in the hypothalamus. The initial reaction is followed by activation of the pituitary gland and secretion of the hormone ACTH. The adrenal gland is activated almost simultaneously, via the sympathetic nervous system, and releases the hormone epinephrine. The release of chemical messengers results in the production of the hormone cortisol, which increases blood pressure, blood sugar, and suppresses the immune system. The initial response and subsequent reactions are triggered in an effort to create a boost of energy. This boost of energy is activated by epinephrine binding to liver cells and the subsequent production of glucose. Additionally, the circulation of cortisol functions to turn fatty acids into available energy, which prepares muscles throughout the body for response. Catecholamine hormones, such as adrenaline (epinephrine) or noradrenaline (norepinephrine), facilitate immediate physical reactions associated with a preparation for violent muscular action and:

• Acceleration of heart and lung action
• Paling or flushing, or alternating between both
• Inhibition of stomach and upper-intestinal action to the point where digestion slows down or stops
• General effect on the sphincters of the body
• Constriction of blood vessels in many parts of the body
• Liberation of metabolic energy sources (particularly fat and glycogen) for muscular action
• Dilation of blood vessels for muscles
• Inhibition of the lacrimal gland (responsible for tear production) and salivation
• Dilation of pupil (mydriasis)
• Relaxation of bladder
• Inhibition of erection
• Auditory exclusion (loss of hearing)
• Tunnel vision (loss of peripheral vision)
• Disinhibition of spinal reflexes
• Shaking

Function of physiological changes

The physiological changes that occur during the fight or flight response are activated in order to give the body increased strength and speed in anticipation of fighting or running. Some of the specific physiological changes and their functions include:

• Increased blood flow to the muscles activated by diverting blood flow from other parts of the body.
• Increased blood pressure, heart rate, blood sugars, and fats in order to supply the body with extra energy.
• The blood clotting function of the body speeds up in order to prevent excessive blood loss in the event of an injury sustained during the response.
• Increased muscle tension in order to provide the body with extra speed and strength.

Emotional components

Emotion regulation

In the context of the fight or flight response, emotional regulation is used proactively to avoid threats of stress or to control the level of emotional arousal.

Emotional reactivity

During the reaction, the intensity of emotion that is brought on by the stimulus will also determine the nature and intensity of the behavioral response. Individuals with higher levels of emotional reactivity may be prone to anxiety and aggression, which illustrates the implications of appropriate emotional reaction in the fight or flight response.

Cognitive components

Content specificity

The specific components of cognitions in the fight or flight response seem to be largely negative. These negative cognitions may be characterised by: attention to negative stimuli, the perception of ambiguous situations as negative, and the recurrence of recalling negative words. There also may be specific negative thoughts associated with emotions commonly seen in the reaction.

Perception of control

Perceived control relates to an individual's thoughts about control over situations and events. Perceived control should be differentiated from actual control because an individual's beliefs about their abilities may not reflect their actual abilities. Therefore, overestimation or underestimation of perceived control can lead to anxiety and aggression.

Social information processing

The social information processing model proposes a variety of factors that determine behavior in the context of social situations and preexisting thoughts. The attribution of hostility, especially in ambiguous situations, seems to be one of the most important cognitive factors associated with the fight or flight response because of its implications towards aggression.

Other animals

Evolutionary perspective

An evolutionary psychology explanation is that early animals had to react to threatening stimuli quickly and did not have time to psychologically and physically prepare themselves. The fight or flight response provided them with the mechanisms to rapidly respond to threats against survival.

Examples

A typical example of the stress response is a grazing zebra. If the zebra sees a lion closing in for the kill, the stress response is activated as a means to escape its predator. The escape requires intense muscular effort, supported by all of the body's systems. The sympathetic nervous system’s activation provides for these needs. A similar example involving fight is of a cat about to be attacked by a dog. The cat shows accelerated heartbeat, piloerection (hair standing on end), and pupil dilation, all signs of sympathetic arousal. Note that the zebra and cat still maintain homeostasis in all states.

In July 1992, Behavioral Ecology published experimental research conducted by biologist Lee A. Dugatkin where guppies were sorted into "bold", "ordinary", and "timid" groups based upon their reactions when confronted by a smallmouth bass (i.e. inspecting the predator, hiding, or swimming away) after which the guppies were left in a tank with the bass. After 60 hours, 40 percent of the timid guppies and 15 percent of the ordinary guppies survived while none of the bold guppies did.

Varieties of responses

Bison hunted by dogs

Animals respond to threats in many complex ways. Rats, for instance, try to escape when threatened but will fight when cornered. Some animals stand perfectly still so that predators will not see them. Many animals freeze or play dead when touched in the hope that the predator will lose interest.

Other animals have alternative self-protection methods. Some species of cold-blooded animals change color swiftly to camouflage themselves. These responses are triggered by the sympathetic nervous system, but, in order to fit the model of fight or flight, the idea of flight must be broadened to include escaping capture either in a physical or sensory way. Thus, flight can be disappearing to another location or just disappearing in place, and fight and flight are often combined in a given situation.

The fight or flight actions also have polarity – the individual can either fight against or flee from something that is threatening, such as a hungry lion, or fight for or fly towards something that is needed, such as the safety of the shore from a raging river.

A threat from another animal does not always result in immediate fight or flight. There may be a period of heightened awareness, during which each animal interprets behavioral signals from the other. Signs such as paling, piloerection, immobility, sounds, and body language communicate the status and intentions of each animal. There may be a sort of negotiation, after which fight or flight may ensue, but which might also result in playing, mating, or nothing at all. An example of this is kittens playing: each kitten shows the signs of sympathetic arousal, but they never inflict real damage.